Cancer screening Biomarker
Collection Type: Blood
Related System: Cancer screening
CA 19-9 (carbohydrate antigen 19-9, sialyl‑Lewis A) is a tumor‑associated glycoprotein shed into the blood by epithelial cells of the pancreas, bile ducts and gastrointestinal tract. The blood test measures serum CA 19-9 concentration and is used primarily as an adjunct marker for pancreatic cancer—also elevated in cholangiocarcinoma, gastric and colorectal cancers—and to monitor treatment response or recurrence. Many benign conditions (acute/chronic pancreatitis, biliary obstruction, cholestasis, cirrhosis) can raise levels. About 5–10% of people (Lewis antigen–negative) cannot synthesize CA 19-9 and will have undetectable results despite disease. Age and sex have little direct effect; results must be interpreted with clinical context.
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Q: What does a positive CA 19-9 mean?
A: CA 19-9 is a blood tumor marker commonly elevated in pancreatic cancer but not specific; levels can rise with other cancers (biliary, colorectal, gastric) and benign conditions (biliary obstruction, pancreatitis, liver disease). A positive (elevated) CA 19-9 suggests the need for further evaluation—clinical assessment and imaging—rather than a definitive diagnosis. It’s also used to monitor treatment response and recurrence; some people don’t produce CA 19-9.
Q: Which type of cancer is most associated with CA 19-9?
A: CA 19-9 is most strongly associated with pancreatic cancer—particularly pancreatic adenocarcinoma. It’s primarily used to monitor treatment response and detect recurrence rather than for screening, because levels can also rise in other cancers (e.g., cholangiocarcinoma) and in benign conditions such as pancreatitis, cholestasis, and liver disease, causing false positives or negatives.
Q: How high can CA 19-9 get before death?
A: No specific CA 19‑9 value predicts death. Normal is <37 U/mL. Levels in the hundreds raise concern for malignancy; values >1,000 U/mL often reflect advanced disease and worse prognosis, and can exceed 10,000 U/mL in late‑stage cancer or biliary obstruction. Clinical context, trends, imaging and overall patient condition determine outcome; interpretation requires physician evaluation.
Q: What is a high CA 19-9 level in ovarian cancer?
A: CA 19‑9 is normally <37 U/mL; levels above 37 U/mL are considered elevated. In ovarian disease, marked rises (e.g. >100–1,000 U/mL) are more often seen with mucinous ovarian tumors or advanced disease, but CA 19‑9 is not specific—benign conditions can also raise it. Interpretation requires correlation with symptoms, CA‑125, imaging and histology; values alone don’t confirm diagnosis.
Q: What are three tumor markers?
A: Common tumor markers include PSA (prostate-specific antigen) used to screen and monitor prostate cancer; CA-125 often elevated in ovarian cancer and used to track treatment response; and CEA (carcinoembryonic antigen) raised in colorectal cancer and some lung, breast, or pancreatic cancers. These blood tests aid monitoring and follow-up but are not definitive for diagnosis and require clinical correlation.
Q: Can fatty liver cause elevated CA 19-9?
A: Yes. CA 19-9 is primarily a pancreatic tumor marker but can be mildly to moderately elevated in several benign conditions, including fatty liver (NAFLD). Liver inflammation, cholestasis or biliary injury in fatty liver can raise CA 19-9 levels. A single mild elevation is not diagnostic for cancer; persistent or high rises should prompt further evaluation (blood tests, imaging, and specialist review).